Protecting mobile agents from external replay attacks

This paper presents a protocol for the protection of mobile agents against external replay attacks. This kind of attacks are performed by malicious platforms when dispatching an agent multiple times to a remote host, thus making it reexecute part of its itinerary. Current proposals aiming to address this problem are based on storing agent identifiers, or trip markers, inside agent platforms, so that future reexecutions can be detected and prevented. The problem of these solutions is that they do not allow the agent to perform legal migrations to the same platform several times. The aim of this paper is to address these issues by presenting a novel solution based on authorisation entities, which allow the agent to be reexecuted on the same platform a number of times determined at runtime. The proposed protocol is secure under the assumption that authorisation entities are trusted.     

A basis for the development of new ammonia–water–sodium hydroxide absorption chillers

Adding NaOH to ammonia/water improves the separation of ammonia in the generator and reduces both chiller driving temperature and rectification losses. In this paper the main disadvantages for the implementation of these new mixtures are addressed: a) few experimental data or reliable correlations of the fluid mixture properties exist; b) selection of an adequate system for separating the hydroxide; and c) evaluation of potential corrosion problems. Our results show that the separation of NaOH from an ammonia/water solution with a maximum approximate mass fraction of 0.05 (5% weight) is viable when reverse osmosis is used with membranes BW30 and SW30HR LE. Cycle simulation using experimental data to calculate the vapour–liquid equilibrium properties shows that the COP is approximately 20% higher than with a conventional ammonia/water chiller working under the same conditions and using a hydroxyl separation efficiency of 99% for NaOH, which is feasible according to the experimental tests.     

Modeling nitrous oxide production during biological nitrogen removal via nitrification and denitrification: extensions to the general ASM models

Nitrous oxide (N(2)O) can be formed during biological nitrogen (N) removal processes. In this work, a mathematical model is developed that describes N(2)O production and consumption during activated sludge nitrification and denitrification. The well-known ASM process models are extended to capture N(2)O dynamics during both nitrification and denitrification in biological N removal. Six additional processes and three additional reactants, all involved in known biochemical reactions, have been added. The validity and applicability of the model is demonstrated by comparing simulations with experimental data on N(2)O production from four different mixed culture nitrification and denitrification reactor study reports. Modeling results confirm that hydroxylamine oxidation by ammonium oxidizers (AOB) occurs 10 times slower when NO(2)(-) participates as final electron acceptor compared to the oxic pathway. Among the four denitrification steps, the last one (N(2)O reduction to N(2)) seems to be inhibited first when O(2) is present. Overall, N(2)O production can account for 0.1-25% of the consumed N in different nitrification and denitrification systems, which can be well simulated by the proposed model. In conclusion, we provide a modeling structure, which adequately captures N(2)O dynamics in autotrophic nitrification and heterotrophic denitrification driven biological N removal processes and which can form the basis for ongoing refinements.     

Muscle Diversity,Heterogeneity, and Gradients: Learning from Sarcoglycanopathies

Skeletal muscle, the most abundant tissue in the body, is heterogeneous. This heterogeneity forms the basis of muscle diversity, which is reflected in the specialized functions of muscles in different parts of the body. However, these different parts are not always clearly delimitated, and this often gives rise to gradients within the same muscle and even across the body. During the last decade, several studies on muscular disorders both in mice and in humans have observed particular distribution patterns of muscle weakness during disease, indicating that the same mutation can affect muscles differently. Moreover, these phenotypical differences reveal gradients of severity, existing alongside other architectural gradients. These two factors are especially prominent in sarcoglycanopathies. Nevertheless, very little is known about the mechanism(s) driving the phenotypic diversity of the muscles affected by these diseases. Here, we will review the available literature on sarcoglycanopathies, focusing on phenotypic differences among affected muscles and gradients, characterization techniques, molecular signatures, and cell population heterogeneity, highlighting the possibilities opened up by new technologies. This review aims to revive research interest in the diverse disease phenotype affecting different muscles, in order to pave the way for new therapeutic interventions.     

First ZnGa2O4 transparent ceramics

Transparent polycrystalline ZnGa₂O₄ ceramics are synthesized, for the first time, by combining high-energy ball milling, solid-state reaction and spark plasma sintering. They appear transparent in both the visible and near infrared (up to 9 μm) ranges after a post-SPS annealing in air converting the raw semiconductor into an electrical insulator. The maximum of transmittance is reached in the near infrared region, at around 2.5 μm, with a value of 78 % (1 mm thick sample) close to the maximum value of transmittance previously measured for single crystals. These transparent ceramics present a classic cubic spinel ZnGa₂O₄ structure and a dense microstructure (> 99 %) attained without sintering aids, with an average grain size of 600 nm and a random orientation of the crystallites. TEM observations performed on thin foils have revealed limited nanometer scale intergranular porosity which does not affect much the transparency. As a proof of interest, red long-lasting luminescence arising from the entire sample volume is observed in these Cr³⁺ doped transparent ceramics. This innovative work is anticipated to further drive the development of transparent ZnGa₂O₄ ceramics towards a wider range of performing optical applications such as laser emission.     

A graded BDI agent model to represent and reason about preferences

In this research note, we introduce a graded BDI agent development framework, g-BDI for short, that allows to build agents as multi-context systems that reason about three fundamental and graded mental attitudes (i.e. beliefs, desires and intentions). We propose a sound and complete logical framework for them and some logical extensions to accommodate slightly different views on desires.     

Design and implementation of a scene-dependent dynamically selfadaptable wavefront coding imaging system

A computational imaging system based on wavefront coding is presented. Wavefront coding provides an extension of the depth-of-field at the expense of a slight reduction of image quality. This trade-off results from the amount of coding used. By using spatial light modulators, a flexible coding is achieved which permits it to be increased or decreased as needed. In this paper a computational method is proposed for evaluating the output of a wavefront coding imaging system equipped with a spatial light modulator, with the aim of thus making it possible to implement the most suitable coding strength for a given scene. This is achieved in an unsupervised manner, thus the whole system acts as a dynamically selfadaptable imaging system. The program presented here controls the spatial light modulator and the camera, and also processes the images in a synchronised way in order to implement the dynamic system in real time. A prototype of the system was implemented in the laboratory and illustrative examples of the performance are reported in this paper.Program summaryProgram title: DynWFC (Dynamic WaveFront Coding)Catalogue identifier: AEKC_v1_0Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEKC_v1_0.htmlProgram obtainable from: CPC Program Library, Queen?s University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 10 483No. of bytes in distributed program, including test data, etc.: 2 437 713Distribution format: tar.gzProgramming language: Labview 8.5 and NI Vision and MinGW C CompilerComputer: Tested on PC Intel^® Pentium^®Operating system: Tested on Windows XPClassification: 18Nature of problem: The program implements an enhanced wavefront coding imaging system able to adapt the degree of coding to the requirements of a specific scene. The program controls the acquisition by a camera, the display of a spatial light modulator and the image processing operations synchronously. The spatial light modulator is used to implement the phase mask with flexibility given the trade-off between depth-of-field extension and image quality achieved. The action of the program is to evaluate the depth-of-field requirements of the specific scene and subsequently control the coding established by the spatial light modulator, in real time.     

Hydropeaking effects on movement patterns of brown trout (Salmo trutta L.)

Radiotelemetry was used to investigate seasonal movement and home range of brown trout Salmo trutta (size range 188–420 mm fork length, N = 30) in two reaches of the Noguera Pallaresa River (Ebro Basin, north‐east Spain) subjected to different flow regulation schemes. NP‐1 reach is a bypassed section with near natural flow conditions, whereas the downstream reach NP‐2 is subjected to daily pulsed flow discharge (i.e., hydropeaking) from an upstream hydropower station. Significant differences in home range size (95% kernel estimates) and seasonal movement pattern between study reaches were found. Mean home range size was (μ ± SE) 112.1 ± 11.5 m in the bypassed reach NP‐1 and increased significantly in the hydropeaking reach NP‐2 up to 237.9 ± 37.2 m. There was a large individual variability in fish home range size within reaches. Most of the seasonal differences in fish movement among reaches were associated with the spawning season. Pulsed discharge events in NP‐2 during daytime in summer (lasting about 3 hr and increasing water flow from 1 to 20 m³/s) did not cause significant displacements in either upstream or downstream direction during the duration of the event. Our results highlight the importance of habitat connectivity in hydropeaking streams due to the need of brown trout to move large distances among complementary habitats, necessary to complete their life cycle, compared with unregulated or more stable streams.     

Validation of 3D neutronic-thermalhydraulic coupled codes RELAP5/PARCSv2.7 and TRACEv5.0P3/PARCSv3.0 against a PWR control rod drop transient

In nuclear safety field, neutronic and thermalhydraulic codes performance is an important issue. New capabilities implementation, as well as models and tools improvements are a significant part of the community effort in looking for better nuclear power plants (NPP) designs. A procedure to analyze the PWR response to local deviations on neutronic or thermalhydraulic parameters is being developed. This procedure includes the simulation of Incore and Excore neutron flux detectors signals. A control rod drop real plant transient is used to validate the used codes and their new capabilities. Cross-section data are obtained by means of the SIMTAB methodology. Detailed thermalhydraulic models were developed: RELAP5 and TRACE models simulate three different azimuthal zones. Besides, TRACE model is performed with a fully three-dimensional core, thus, the cross-flow can be obtained. A Cartesian vessel represents the fuel assemblies and a cylindrical vessel the bypass and downcomer. Simulated detectors signals are obtained and compared with the real data collected during a control rod drop trial at a PWR NPP and also with data obtained with SIMULATE-3K code.